Ancient lake on Mars could have sustained life, researchers say

This illustration depicts a concept for the possible extent of an ancient lake inside Gale Crater. The existence of a lake there billions of years ago was confirmed from examination of mudstone in the crater’s Yellowknife Bay area. For this illustration, the possible extent was estimated by mapping ancient lake and stream deposits and recognizing that water flowed from the crater rim into the basin (arrows).
Image courtesy: NASA’s Jet Propulsion Laboratory

The rover Curiosity found evidence of an ancient lake that could have supported life as we know it for possibly millions of years. The results were detailed among six different papers published Monday in the journal Science.

The lake, about 30 miles long by three miles wide, was located at the base of Mount Sharp in Yellowknife Bay and believed to have been filled with fresh water at least 3.7 billion years ago. Though that water is long gone, the clay sediments and formations left behind contain clues of a soggier, life-sustaining version of the dry, barren Mars we know today.

“The rocks that we drilled into were very fine grain rocks called mudstones,” Curiosity deputy project scientist Ashwin Vasavada said. “Those kind of fine grain sediments, you’d expect to settle out in a lake.”

Samples extracted by Curiosity’s drill and studied by the rover’s Sample Analysis at Mars (SAM) software marks the first time nitrogen has been detected on Mars, according to Doug Ming, lead author of the new report and a soil mineralogist at NASA Johnson Space Center. Other building blocks of life like carbon, oxygen, hydrogen and phosphorus were also found in the minerals.

“Quite honestly, it just looks very Earth-like,” Curiosity lead scientist John Grotzinger told Space.com.

Curiosity landed on Mars in August 2012 with the goal of finding evidence that the Gale Crater could have supported microbial life.

The ancient lake could have supported a class of microbes called chemolithoautotrophs, which obtain energy by breaking down rocks and minerals, according to a news release. The class of microbes can be found in caves and hydrothermal vents on the ocean floor.

“We have no evidence in our data that there were microbes in this material,” Ming said. “Now with that said, we do have evidence of elements necessary for life.”

The mudstones discovered in Yellowknife Bay usually form in calm, still water. A river once flowed from the northern part of the 96-mile-wide Gale Crater before it fanned out and emptied into the lake.

“If the water was just flowing out of a river you’d expect it to be more lumpy, but if the sediment is flowing into a lake, it just gets mixed inside the lake and gravitationally settles out over a long period of time, and forms layers of sediment over the bottom.”

Based on the samples of sediments extracted by Curiosity, the PH of the water was neutral — not too acidic, not too neutral — and life could have made use of it, Vasavada said. Some scientists believe water on Mars evaporated.

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“When this water presumably existed, the atmosphere was more stable,” Vasavada said. “There’s a lot we don’t know about the environment back then.”